An experimental study of molecular and conformational order of the phosphotidylcholine molecule in the bilayer membrane is proposed. Furthermore, the effect of insertion of protein into the bilayer on that molecular and conformational order is to be investigated. A new multi-order parameter approach is to be applied to the interpretation of deuterium magnetic resonance spectra from specifically deuterated sites in the phospholipid molecule. From this approach one is able to obtain new information concerning restricted rotation of the phospholipid molecule. From this approach one is able to obtain new information concerning restricted rotation of te phospholipid about its long molecular axis and added information concerning its time-average conformation. In addition, phase transitions of aqueous multilamellar dispersions of phospholipids, specifically 2H-labeled, will be examined by 2H NMr spectroscopy. Initial studies carried out for DMPC-2-(14', 14', 14'-d3) and DPPC-3(16', 16', 16'-d3) will be extended to more complex systems containing a protein, another phospholipid, or another phosphatidylcholine with an unsaturated 2-fatty acid substituent. These measurements combined with the above multiorder parameter based analyses of the data should provide a description of changes in molecular orientation which occur at the phase transitions of phospholipids.